1. All things on this Earth are either elements or molecules made from elements. Molecules can be small or very large. Large molecules must be broken down before they can be used by the human body.
2. Take carbohydrates, for instance. They are composed of carbon, hydrogen, and oxygen. We get carbohydrates when we eat grains like wheat and corn. The word carbohydrate means watered carbon, that is, carbon with attached water molecules. The molecules can be quite long. They must be shortened to be used by the human body.
3. Our bodies convert carbohydrates into energy. However, most carbohydrates are too large to absorb. The digestive system breaks down large molecules into smaller ones. One example is starch breaking down into glucose. Once inside the body, those molecules are broken down into even smaller ones. Energy is released. The released energy helps keep the human body going.
4. The break down process starts in the mouth. When you eat a saltine cracker, it tastes salty in your mouth. However, keep chewing it for several minutes. Your mouth will begin to notice a change. The cracker does not taste as sweet in your mouth at first if you chew it for five or ten minutes. That is because the cracker is a carbohydrate. An enzyme in your saliva helps turn the cracker to sugar. The resulting glucose molecules are what the body needs from that cracker.
5. Molecules come in all shapes and sizes. The human body cannot make use of very large molecules in food. We rely on a chemical change that happens in the digestive system. Large molecules break down into smaller molecules that can be absorbed and used.
QUESTION 1
Carbohydrates are found in many foods. What is the end result of the body’s use of a carbohydrate?
OPTIONS
A carbohydrate is used as it is to build up the body.
A carbohydrate is broken into glucose, which makes the body move.
Carbohydrates are combined to make a large carbohydrate.
A carbohydrate is broken into glucose, which is broken into smaller molecules to release energy.
QUESTION 2
How will a saltine cracker start to taste if someone chews on it for five minutes?
OPTIONS
very salty
bitter
sweet
hot
QUESTION 3
What does the word enzyme in paragraph 4 mean?
OPTIONS
the glands which produce saliva in your mouth
a substance that helps a chemical change occur
a large carbohydrate molecule
a simple sugar
QUESTION 4
What is the main focus of the passage?
OPTIONS
A cracker will change as you chew it.
Some molecules must be broken down to be useful.
All molecules are small.
The process of digestion is explained.
ANSWER 1: A carbohydrate is broken into glucose, which is broken into smaller molecules to release energy.
ANSWER 2: sweet
ANSWER 3: a substance that helps a chemical change occur
ANSWER 4: Some molecules must be broken down to be useful.